Candidates Use Second G.O.P. Debate to Taunt Donald Trump

SIMI VALLEY, Calif. — Determined to prove their mettle, several Republican presidential candidates showed new aggressiveness in lacing into Donald J. Trump on Wednesday night, seeking to elevate themselves as leaders of substance and shake up a race that Mr. Trump has dominated all summer.

While moderators at the CNN debate tried repeatedly to pit one Republican after another against Mr. Trump, the candidates fought to break out of that dynamic, with Carly Fiorina emerging as an especially tenacious combatant who provided some of the few moments where Mr. Trump looked uncomfortable.

Of course, any time Donald Trump is uncomfortable, well, that’s comforting.